Automatic musical instrument



Aug. 4, 1931. c. F. sToDDARD AUTOMATIC MUSICAL INSTRUMENT Original Filed June 18, 1926 5 Sheets-Sheet l SNN QN.

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Aug. 4, 1931. c. F. s roDDARD AUTOMATIC MUSICAL INSTRUMENT originai Filed June 18, 1926 5 Sheets-Sheet 2 BZ IIy/ENOR. 7

Aug. 4, 1931. c. F. sToDDARD AUTOMATIC MUSICAL INSTRUMENT 5 Sheets-Sheet .'5

Original Filed June 18 1925 Aug. 4, 1931. c. F. sToDDARD AUTOMATIC MUSICAL INSTRUMENT Original Filed June 18, 1926 5 Sheets-Sheet 4 2 INVENT0R.7

A BEV/EW Aug. 4', ,1931. c. F. sToDDARD AUTOMATIC MUSICAL INSTRUMENT 5 sheets-sheet 5 Original Filed June 18, 1926 Patented Aug. 4, 1931 unirse s'rATEs PATENr OFFICE CHARLES F. STODDARD, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO

All-IERICAN PIANO CORPORATION, OF EAS OF DELAWARE T ROCHESTER, NEW YORK, A CORPORATION AUTOMATIC MUSICAL INSTRUMENT Original application` filed .Tune 18, 1926, Serial No. 116,787.

Divided and this application filed July 12, 1928.k

Serial N0. 292,216.

This invention relates to automatic musical instruments and pertains more particularly to mechanisms and methods for improved expression control, or Vtor imliiro'ving the control of the dynamic 'forces with which individual notes or groups of notes of a giren composition are sounded.

' The apparatus illustrated in the drawings and described more particularly hereinafter relates especially to that class orn instruments now known to the trade and general public as reproducing pianos, because they are intended to reproduce, automatically, under control of a perforated note sheet, the inanual performances of artists or other pianists.

In such pianos, it is customary to provide a series of striker pneumalics which are connected to the usual hammer actuating mechanisms t the piano in such manner that when the said striker pneumatics are collapsed, the hammer actuating means are operated to cause the hammers to strike the strings. It is also customary in such pianos to provide means for operating the dampers of the piano in order lo simulate the effects which are secured by a pianist in using the loud pedal, lt has been found, however, thatJ when the dampers are lifted by such mechanisms variations vin tone intensities result which all'cct 'the lidelity of reproduction ol the instrument, for the reason that the presence or absence of the weight oli the dampers makes less or .more effective the blow imparted to the hammer by the striker pneumatics for any given degree orn regulated exhaust. It is an object of the present invention to provide means to compensale for such variations in order that for any given degree of regulated exhaust, the hammer shall be actuated with the same force regardless of whether or not the mechanism for operating the dempers is in use.

This application is a division of my previous application Serial No. 116,787, tiled June 18, 1926, for automatic musical instruments. A

Other objects and advantages of the invention will appear hereinafter.

A preferred embodiment of the invention selected for purposes of illustration is shown in the accompanying drawings, in which,

Figure 1 is a diagrammatic view showing the pneumatic connections between the cooperating units of the apparatus.

Figure 2 is a semi-diagrammatic sectional View taken through the stack and expression mechanism.

Figure 3 is a longitudinal section taken on' the line 3-3 of Figure 2.

Figure el is a section through the bass eX- pression valve mechanism. l

Figures 5 and 6 are top plan and rear ele-` val'ion views respectively of the stack. w

Figure 7 is a longitudinal section taken on the line 7-7 of Figure 2.

Figure 8 is a section through the stack showing in section one of the dummy valves for controlling the lost motion pneumatica Figure 9 is an enlarged sectional view illustrating the consruction and operation of the regulator.

Figure 10 is a sectional view of the pedal pressure regulator.

Referring to the drawings, the striker or player pneumatics 1 are provided which are connected by rods 2 to levers 3 pivoted to a fixed part of the piano structure at il. The outer ends of the levers 3 lie underneath the rear ends of the keys 5 of the piano and are adapted to actuate the keys through the adjustable screvs l mounted in the end of the levers 3. Movement of the keys operates the usual hammer actions 7 to actuate the hammers 8 to strike the piano strings 9 in the same manner that the hammers are actuated when the piano is )layed manually. Upward movement of t e keys 5 also actuates the levers 10 'to lift the dampers 11 from the strings to permit free vibration thereof in the usual manner. As will be understood, a sutlicient number of striker pneumatics l are provided to operate the entire piano action. i

Each of the striker pneumatics 1 is connected by a passage 12 to the valve chamber 13 of a valve unit 14 which may be connected to the tracker bar 15 by a suitable duet 1G. The valve units 14 and the striker pneumatics 1 maybe conveniently mounted oai on opposite sides of a board 18 which is provided with a series of vertical passages 19 to which the exhaust chambers Q() of the valve units are connected through the passages 21. Each of the passages 19 is connected with a compartment which may be conveniently divided by the partition Q2 into two sections and 23', one for the bass and one for the treble section of the piano. Each section of this compartment, together with the passages 19 leading therefrom to the valve units, may be referred to as a regulated exhaust chest, since as will be hereinafter explained, the exhaust therein is regulated by the mechanisms provided te control playing intensities.

As will be understood, the force of the blow delivered by a hammer to a string by the collapse of a motor pneumatic will depend largely upon the degree of exhaust maintained in the regulated exhaust chest. That is, if a high degree of exhaust is maintained in said chest, the collapse of any given pneumatic, when its controlling valve is operated to subject the pneumatic to exhaust,r will be more rapid than when the degree of exhaust maintained in the chest is less. It will thus be apparent that by varying the degree of exhaust maintained i the regulated exhaust chest, the force of the blows delivered to the strings by the collapse of the motor pneumatics may be varied, and further that by maintaining the degree of exhaust therein substantially constant the force of the blows delivered to the string may be maintained substantially constant.

In the present embodiment means are provided for governing the degree of exhaust maintained in the regulated exhaust chest and for thereby governing the force of the blows applied to the strings of the piano.

For purposes of explaining the general character of the regulator and to exemplify one practical embodiment thereof for controlling the degree of exhaust maintained in the wind chest, the apparatus particularly shown in Figures 2 and 9 of the drawings has been selected in which the high exhaust chest is connected by a conduit 26 to a reservoir bellows Q7 which is connected, as will be hereinafter more fully explained, through conduit Q8 to a suitable source of exhaust 99. Any of the well-known forms of exhaust means may be employed in connection with the present invention, that shown herein comprising the ordinary bellows type pump driven by an electric motor 30. A pump pressure controlling mechanism designated generally by reference numeral 31 may be operatively connected to the conduit 2S through conduit 32, the said mechanism serving to control the exhaust supplied by the pump to the reservoir 27.

Means are profided for controlling the degree of exhaust maintained in the regulated exhaust chests 23 and 23', as for example by restricting more or less communication between said chests and the high exhaust chest 25. In the specific illustrative embodiment of the apparatus shown in the drawings, this restrictive action is performed by a movable member of very little weight, influenced, as will be hereinafter explained, by the pneunmtic forces to which it is exposed. This movable member arranged to cooperate with a fixed supporting member which comprises, in the present embodiment, a plate or screen 33 provided with a mu tiplicity of perforations 34 to permit the passage of air.

In the embodiment illustrated, the movable member comprises a diaphragm or membrane 35 of leather, rubber cloth, or other suitable nexible material. Preferably, this movable member is arranged to have one side exposed partly to the high exhaust maintained in the chest and partly to the regulated exhaust maintained in the chest 23. .1l-.s shown, the diaphragm in operation extends alone the plate or screen in position to cooperate therewith to con trol the passage of air therethrough from the chest 23 to the chest 25, thus forming in ell'ect a valve controlling the flow of air from the action or regulated exhaust chest to the high exhaust chest.

Means are provided to act upon the mov able member, herein the diaphragm 35, in such manner as to increase therelfect of high exhaust upon regulated exhaust. as for example, to tend to peel the diaphragm away from the screen or plate to thereby increase the effective opening between the chests. The said means herein includes a chamber 36, which may be known as a controlled exhaust chest, separated from the regulated exhaust chest Q3 and the high exhaust chest 25 by the diaphragm 35, and means to maintain in said chamber a cer tain degree of exhaust, which for the present may be assumed to be constant, although as will appear later, this degree of exhaust may be changed for the purpose of securing expression variations.

ln the specific embodiment of the invention illustrated the chamber 36 is connected through a. conduit 3T to the reservoir 27. a bleed opening 3S being interposed in the passage to `constrict the communication therebetween. As will readily be understood, any desired degree of exhaust less than high exhaust may be maintained in the chamber 3G by the relative adjustment of the sizes of the bleed opening 38 and certain atmosphere vents opening into chamber 36 hereinafter described, and preferably said degree of exhaust is maintained at a somewhat higher level than the desired degree of regulated exhaust, the precise degree Ile lift

depending upon the particular design and arrangement of the parts. The passage 37 leading to the reservoir 27 may preferably enter the same at a point near the hinged end thereof in order that the exhaust communicated to the controlled exhaust chest 37 may be influenced as little as possible by the aspirative effect of currents of air which may pass through other portions thereof, for, as will hereinafter appear, it is desirable to maintain controlled exhaust as far as possible without fluctuation.

The differential between high exhaust in chest and controlled exhaust in chest 36 acting on that part of the diaphragm exposed to high exhaust will exert an upward force urging the diaphragm against the screen 33 to thereby cover the perforations of the screen to prevent the passage of air therethrough and to restrict communication between high and regulated exhaust chests. On the other hand, the differential between regulated exhaust in chest 23 and controlled exhaust in chest 36 acting upon that part ,i of the diaphragm exposed to regulated exhaust exerts a downward force urging the diaphragm in a downward direction. As will be apparent, this downward force will tend to peel a' portion of the diaphragm subjected to high exhaust away from the screen 33 thus serviner to o en certain 'erforations to permit the passage of air therethrough. Thus the area of the diaphragm exposed to high exhaust may be divided into two portions. That portion which is forced against the screen by the differential of pressures acting thereon may be termed an inactive or dead area, and that portion which is drawn away from the screen by the action of pneumatic forces thereon may be termed an active area. As will be observed, the active area subjected to high exhaust may vary as the diaphragm is peeled away from the screen or returned thereto in operation.

Assuming that the forces exerted on the diaphragm by high exhaust and controlled exhaust remain substantially constant, a condition cf equilibrium is established such that regulated exhaust will also be maintained substantially constant, because if, for example, regulated exhaust tends to increase then the downward force of the differential between regulated exhaust andcontrollcd exhaust is decreased and a tendency toward an upward movement of the diaphragm results. This in turn tends to further restrict cemmunication between the high and regulated exhaust chests by closing certain of the perforations 34, permitting regulated exhaust to be decreased by the influx of air until the condition el" equilibrium is restored'. On the other hand, iii regulated exhaust tends to decrease, then the differential between regulated exhaust and controlled exhaust tends to increase with the result that there is a tendency toward a downward movement of the diaphragm to open additional perforations 34 to thereby increase the effective opening between the high and regulated exhaust chests, thus permitting additional air to be withdrawn from the regulated exhaust chest to thereby increase the degree oit" exhaust maintained therein until the condition of equilibrium is restored. Thus there is a constant tendency on the partf tliediaphragm to maintain a position such that the balanced condition shall always prevail.

In the ordinary operation of the piano, several factors may act separately or may combine tending to cause va tions in regulated exhaust. For example, there may be more or less constant leakage ot atmospheric air to the regulated exhaust chest, which, even though slight, tends to reduce regulated exhaust. Vly the action just described, however, this would result in a movement of the diaphragm suflicient to permit a corresponding leakage to the high exhaust chest through the perforations 34, thus permitting regulated exhaust to remain substantially constant.

As a. further example, in the normal operation olf the piano by the motor pneumatics l lunder control of the usual note sheet, e ch of the motor pncuinatics before collapse is filled with air at atmospheric pressure. Immediately that the valve 14 is op'- erated to collapse the pneumatic 1 there is an inrush of' atmospheric air into the wind chest past the valve as it travels from one seat to another, followed immediately by the air that is withdrawn from the pneumatic as it collapses.

Due to the action just described, whenever such an inrush of air occurs, the force of regulated exhaust acting upwardly on the diaphragm thereby tends to decrease thus permitting the diaphragm to be peeled away from the plate 33 to thereby open additional perforations to permit a corresponding 'quantity of air to be withdrawn to the high exhaust. chest. Consequently, there is a tendency to increase regulated exhaust until a condition of equilibrium is again reached. y

Such action may take place so promptly and quickly, that, in effect, the action is to maintain the degree of exhaust in the regulated exhaust chest substantially constant, or, in other words, the practical effect is that of maintaining rather than correcting. And this capacity of the apparatus to maintain a constant degree ot' regulated exhaust rather than to correct changes in regulated exhaust is increased over prior art structures having a similar capacity due to the fact that the diaphragm is substantially without inertia. In other words, such action as occurs results almost wholly from the action of juxtaposed pneumatic forces upon each other, and there is no' lag or overthrow such as would otherwise occur with parts haring substantial weight.

This capacityo' the apparatus to inanitain a constant degree ot regulated exhaust is also increased over prior art structures due to the con 'rue-tion and arrargement ot' the l wheneoy the regulator placed in cl( proximity to theplayer pneuinatics. Due to this provi ion the wares of' pres e or change of pressure have a less distance to travel than in prior art structures in which the regulator and action wind chest have been aiianged separate units connected by suitable conduits or wind trunks and consequently an increase in the speed of the regulating action is noted. it will also be observed that in the embodiment ot the invention illustrated herein the regulatorl extends for a substantial distance along the bottom of the wind chest and thereby provides direct communication between the regulator and the most frequently used player pneu- :natics in the middle range oi' the instrument.

Thus, in the playing of a single note there may be sereral contributing ,factors tending to reduce regulated exhaust below its normal level which, it not compensated i'or, might reduce the force 'ith which the blow is struck. iis has been explained, however, the restoring action operates so quickly due to he absence of inertia that in practical ect regulated exhaust is maintained substantially constant.

briously, in the operation of a piano the number ot motor pneumatics operated during the playinfr et a musical composition 'varies widely from time to time. As will be apparent, however, due to the action ust described, the degree of exhaust maintained in the regulated exhaust chest and the wind chest will tend to remain substantially constant no mat er how many motor pneuinatics are operated given tim and the ef- ;tectire opening een the high and reguwill be automatically ae regulated exhaust chest. been assumed that the deiaintaii l in the controlled substantially conexerts substantially 'inward pull on tue diaphragm f i, the apparatus thus iar has been considered purely as a regulator. Means are provided, however, acting in conjunction with the reg 1fitor for changing the degree of exhaust n ntained in the controlled exhaust chest to liaustchest.

l etere na.

pose, it may be convenientto consider the el'lect of a change in controlled exhaust on the operation oi' the apparatus, and particularly on regulated exhaust. As has been cxplained, regulated exhaust and high exhaust exert an upward pull on the diaphragm, while controlled exhaust exerts an opposed downward pull thereon. Consequently, as-

suming that high exhaust remains substantially constant, an increase in controlled cxhaust must result in an increase in regulated exhaust in order that the condition ot' equilibrium may be maintained. rthat is, haring increased the torce acting downwardly ou the diaphragm, the torce acting upwardly must also increase in order to maintain the condition ot equilibriun. As a spe-iy ciiie exan'iple ot' what may occur under these conditions, it controlled exhaust is increased, there first results a tendency to peel the diaphragm away from the plate 33 thus opening additional pertorations to pera la rger quantity of air to be withdrawn trom the regulated exhaust chest whereby the exhaust therein is increased. This increase in turn exerts an increased upward pull on the diaphragm tending to return it somewhat toward the plate to restore a condition of equilibrium at the higher level of regulated exhaust. In like manner any dein controlled exhaust will cause a desc in regulated exhaust and in the de- Citar. grec of power applied to the strings by the hammers.

has been set forth before, the particular degree ot exhaust maintained in the controlled exhaust chest 36 depends on the relative sizes of the separate rents leading from this chamber to the reservoir and to the atmosphere. Obviousl` if the size of the vent to atmosphere is increased controlled exhaust will be decreased and conversely if the size ot the vent to atmosphere is decreased, controlled exhaust will increase. Means are novided for varying the size of the vent to atmosphere by distinct increments in order that controlled exhaust and hence regulated exhaust may be varied to thereby obtain incremental expression variations in playing.

For this purpose there are provided, leading into the chamber 36 a plurality of vent passages 40, Ll@ and 40?) in which may be placed bleed cups ll, Alla and 41o, the cups being provided with openings of progressively increasing areas, the opening in the cup 4l being the smallest opening, the opening in the cup Llla, being somewhat larger and the opening in the cup 4l?) being the largest. Then all of the passages 10, 40a and 40,7) are opened to permit the passage of atmospheric air to the controlled exhaust chest 36, play-'ing intensities will be at their softest, because the large inflow of atmospheric air relative to the small outflow through the eonstricted passage 37 causes only a slight degree of exhaust to be maintained in chest 36, and as before explained, a relatively low degree of exhaust will be maintained in the regulated exhaust chest 23. On the other hand, as one or more of the passages 40, a and 405 are closed to prevent the passage of atmospheric air to the controlled exhaust chest 36 the degree of exhaust maintained therein is increased with corresponding increases in the exhaust maintained in the regulated exhaust chest 23.

In order to close the passages 40, 40ay and 405, the pouches 42, 42a and 42?) are provided having relatively flat stiiliened portions 43, 43a and 431) serving as valves to cover the outer ends of the passages. The pouches 42, 42a and 42?) are mounted Within a chamber 44 having a conduit 45 leading to atmosphere and are provided with light coil springs 46, 46a and 465 which assist in returning and holding the valves 43, 43a and 432) on their seats. Leading to the inside of each ot' the pouches is a duct 47, 47a and 47?) which may be connected to a valve mechanism hereafter described for supplying either exhaust or atmosphere to the pouches. As will be apparent, when the pouches are subjected to exhaust, a dilerential of pressure is created which forces the pouches downward away from the passages 40, 40@ and 40?) thereby opening the same. On the other hand, when atmosphere is admitted to the pouches, the pressure differential is reversed, the pouches are returned to their seats under the influence o t' the springs 46, 46a and 46?) and are retained thereon under the combined influence of the springs and the pressure differential.

In order that the pouches may be con trolled automatically from the tracker bar the valve mechanism 5() is provided having a chest 51 connected to high exhaust through the conduit 52.

Inasmuch as the valve mechanisms for controlling the bass and treble sections of the piano are duplicates only one Will be described in detail herein, it being understood that a valve mechanism is provided for controlling the treble section of the piano in a manner similar to that in which the valve action 50 controls the bass section of the action.

The valve action 50 includes three valve units 53, 53a and 535 connected to the pouches 42, 42a. and 42?) by the ducts 47, 47a

and 47]) respectively. Inasmuch as each of these valve units are of the same construction only one will be described in detail herein. The duct 47 is connected to a valve chamber 54 controlled by a duplex valve 55 arranged to control a port 56 to atmosphere and a port 57 leading to the exhaust chest 58, said exhaust chest 58 being connected to the chest 51 through the passage 59.

The valve is controlled and loperated by a diaphragm 60 covering the diaphragm chamber 6l into Which opens the duct 62 leading to the tracker bar 15. When the tracker bar vent 63 controlling the admission of atmosphere to the duct 62 is opened, the differential of pressure between the diaphragm chamber 61 and the exhaust chest 58 causes the valve 55 to be raised to close the port 57 tothereby cut off exhaust from the chamber 54 and to open the port 56 to thereby admit atmospheric air to the chamber 54. Thus, under normal conditions with the tracker bar vent 63 closed and the valve/55 lowered the chamber 54 is maintained under exhaust from the exhaust chest 58 and when the valve 55 is raised atmospheric air is admitted to the chamber 54 and exhaust is cut olf.

lVhen the valve 55 is once raised by venting the tracker duct 62 the valve preferably remains in raised position even though the tracker vent may be immediat-ely closed. In the specific apparatus illustrated, this results from the fact that once the valve 55 is opened to admit atmosphere to the valve chamber 54 said valve 55 is held in that position by atmosphere admitted past the valve 55 into a duct 64 from which it passes through a bleeder vent 65 through the duct 66 which communicates with the diaphragm chamber 6l. Thus so long as atmosphere is admitted through the duct 64 the diaphragm 60 will remain lifted and atmosphere will continue to be admitted to the chamber 54.

F rom the preceding discussion it will appear that small perforations in a note sheet controlling the tracker vents 63, 63a and 63?) may be employed which may be immediatelv closed if desired. When used with the illustrativeapparatus each such perforation has the effect of introducing atmosphere to one of the chambers 54, 54a; and 541) and even after the tracker vent is closed atmosphere will continue in the corresponding chamber until purposely exhausted at any subsequent time in a manner such as that about to be described.

In the preferred embodiment of the apparatus illustrated in the drawings, a single valve mechanism controlled by a single tracker vent is employed to cooperate with all or any of the three above described valve mechanisms to negative the effect of opening one or more tracker vents 63, 63a and 63?). Such valve mechanism is designated in the drawings by 71. This valve mechanism comprises a valve chamber 72 controlled by a duplex valve 73 arranged to open the port 74 to atmosphere and to close the port 75 to exhaust from the chest 76 connected to the exhaust chest 51 by means of the duct 77. The valve-is operated by dia hragm 78 mounted over the diaphragm c amber 79 which communicates by means of the duct 80 with a tracker vent 51.

lllhen the tracker vent 8l is opi red by a suitable opening in the note sheet, atmosphere is admitted to the diaphragm chambe T9 and the dillerential of pressure between the diaphragm chamber and the exhaust chamber 7G causes the valve 73 to be raise; to cut oli exhaustirom the Calvo chamber 'TQ and to permitatmosphcric air to enter the chamber.

As alreadurv stated, the Yalre is held in raised position by the atmosphere which is admitted to the diaphragm chamber G1 through the ducts 66 and 64, As will be apparent, it communication between these ducts is cut otl1 and suction applied to the duct -G the di'derential of pressures which causes the valve 55 to be raised would be equalized and the Valve 55 would return to its normal position. Means are provided tor performing this operation, such means comprising the valre S5 which normally re.- mains in seated position coter-ing the port- 86 leading to the exhaust chamber 58. lt this valve is raised, the port 86 will be closed thus cutting off communication between the ducts 6l and GG. At the same time the valve chamber 8T will be subjected to exhaust through the port 8G and this exhaust communicated through the bleed rent G5 and yduct GG Will cause the valve 55 to return to normal position as before described.

The Valve is operated by diaphragm SS covering the diaphragm chamber 89 rhich is in communication With the valve chamber T9 beiiore described through the duet 90. Accordingly, When the valve 73 is in its lowered position the diaphragm chamber 89 is subjected to exhaust and th `5 remains in lowered position. lVhen ralre 73 is raised by the admission of spheric air through the tracler Vent Sl, sphelic air is also admitted to the diaein chamber S9 with the result that the S5 is raised and the valve is returned to normal position. In this :manner by opening the traeler vent Sl any of the chambers 5l, 5l@ and 5417; which have been opened to atmospheric air are again subieeted to exhaust.

The operati ,n just described so far as it concerns the .specific illustrative mechanism depends upon leeding the diaphragm cha .i ier 6l. lf the tracker duct 62 be openefl through its vent at the same time the rent 8l is opened to initiate the bleeding oi the diaphragm chamber 6l, atmosphere will enter the chamber (il more rapidly than it can exhausted therefrom by the described bleeding, and, therefore, the effect ot' opening the vent 8l is negatived and nude: such circumstances the Val-Ve will remain. in r ised position and atn'iosphere will continue to be admitited to the chamber 5l..

Aliso. it the tracker vent 63 for instance be opened simultaneouslyy with the tracker vent Si, the latter will inaugurato a tendency to bleed the chamber 6l and, keep the valve lowered in the position shown, but the sin'iultaneous opening of the tracker vent 63 will admit atmosphere to the cnamber 6l more rapidly than it eau he exhausted by the bleeder vent and, therefore, the valve 55 will be lifted in spite of the opening of the tracker vent Sl.

From the above desorption it will be understood that Whether or not the tracker Vent Sl be opened, the opening of any of the rents (33, (3i-la. and (535 will have its normal and usual etlect to admit atmosphere to the appropriate chamber 5l, 5-l-a or 547). This will be true if any rent 63, (33a or 6Fl?) be opened with or without simultaneously opening the tracker vent 8l.

On the other hand, il the rent G3 be opened and then closed atmosphere being thereby admitted to the chamber 54, and the rent Sl be thereafter opened, the previous etl'cct ot opening vent (3i-i Will be negatived and the chamber 5i will be opened to exhaust.

In the operation of the apparatus thus tar described it may be desirable under certain conditions to vent atmospheric air to the regulated exhaust chest'. For example, this might be particularly desirable in maling sudden changes in regulated exhaust om a condition ot relatively high exhaust o one of relative y lou' exhaust in order that the condition ot high exhaust may be immediately relieved. For this purpose means are provide-:jl for renting atniospheric air to the regulated exhaust chest and such means are preferably controlled by the automatic valve mechanism Which controls the degree of exhaust maintainer therein.

In the preferred embodiment illustrated, the regulated exhaust chest 23 is provided with ay rent 91 to atmosphere, said Vent being controlled by the diaphragm 92 mounted on the bloei; 98. The block 03 is recessed to provide a chamber 9i behind the diaphragm and the chamber 9i is connected by duct 95 with the duct To leading to the diaphragm chamber 545 controlling the rent. 40?). 'l`hns, when the duct l'TZJ is subjected to exhaust to operate the diaphragm 425 the duct 05 is .likewise subjected to exhaust to raise the diaphragm It will, therefore, be apparent that at any time when rent 4l?) is open or that in making any change in regulated exhaust involving the opening of the vent 41?), the vent 91 will also be opened to pemit the entrance of atmospheric air to the regulated exhaust chest. lt will also be apparent that while the opening of the rent 91 permits an inrush of atmospheric air to relieve any temporary undesirable condition of exhaust, the continued flouY ot atmospheric air through the Vent will not affect the operation of the instrument for the leakage of air Will be compensated by a corresponding leakage past the diaphragm as hereinbefore explained.

Indeed the flow of air through the vent 91 and through the regulator past the diaphragm while playing the lower intensities which prevail Whenever the vent 415 is open may be of positive advantage, for it has been found that the regulator sometimes operates more sensitively With an` appreciable How of air than is the case when little or no air is flowing therethrough.

The apparatus thus far described has the capacity of maintaining in the regulated exhaust chest a substantially constant degree of exhaust regardless of the number of motor` pneumatics operated at any given time, and regardless of the varying' amounts of air admitted to t-he regulated exhaust chest therefrom. It likewise has the capacity of varying the degree of exhaust maintained in the regulated exhaust chestJ by a series of substantially distinct steps or increments Which produce similar distinct steps or increments in the intensity of the successive notes played by the instrument due to the varying force of the blows imparted to the strings by the hammers. As has also been noted, the degree of exhaust established in the regulated exhaust chest will be maintained substantially constant at any of the several degrees at which it may be set by changing the degree of exhaust in the controlled exhaust chest.

For the purpose of controlling the operation of the loud or damper pedal mechanism the pneumatic 220 may be provided which is operatively connected to the damper rail 221 through the rod 222. As will be apparent, upon collapse of the pneumatic 220 the damper rail 221 Which extends across the entire piano will be raised to lift all of the arms l0 thus lifting all of the dempers 1l from the strings 9 to permit the same to vibrate freely in the usual manner. Pneumatic 220 is connected ly means of a conduit 223 with the valve chamber 224 of the valve unit 225, the diaphragm chamber 226 of the unit being connected to the tracker bar through the duct 227. The exhaust chamber 228 of the valve unit is connected to the source of exhaust in a manner described more in detail hereinafter through the conduit 229. lVhen a suitable opening in the tracker bar uncovers the tracker vent 230, the valve 231 is raised, pneumatic 220 is subjected to exhaust and is collapsed to lift th dampers ll.

As Will be observed, when the damper-s are lifted in the manner just described a certain amount of Weight is removed from the keys 5, and the amount of energy which is necessary to strike a bloW of any given intensity to the Strings is thereby decreased due to the fact that the dampers do not have to be lifted by the striker pneumatics. In other Words, in order to strike a blo7 of the same intensity When the dempers are lifted less energy need be applied.

In the present embodiment means have been provided by which under certain conditions when the pedal mechanism is operated to lift the damper-s, regulated exhaust is automatically decreased by a certain amount so that at all times regardless of Whether the dampers are raised or lowered the blow imparted to the string Will be of the same intensity. For this purpose the valve chamber 224.- of the valve unit 225 is provided with a duct 232 which may be divided to provide a duct 232, said ducts leading respectively to the chambers 233 and 233 (see Figure 3) for the base and treble sections of the piano. As the chambers and 233 are similar in construction and operation only one will be described in detail herein. The chamber 233 is covered by a diaphragm -34 having a relatively flat stiflened portion 235 adapted to close the end of the vent 286 having a bleed 237 arranged therein. Above the diaphragm 23d; is a chamber 238 Which communicates with the passage 4G?) through the duct 259. l/Vhenever the diaphragm 42?) is lowered, the chamber 238 is in communication with the chamber 4.4: and diaphragm is subjected on one side to the atmosphere admitted through duct and on the other side to atmosphere admitted to chamber 233 through the duct 232. Under' these conditions, therefore, the vent 236 is closed by thc light coil spring 240.

If, under these conditions, the valve 23 is operated to collapse the pneumatic to raise the dampers, the chamber 2533. is also suly :cctcd to exhaust through the duct 232, the diaphragm 23d is lowered and air may pass through the duct 239 through vent and bleed 237 to the controlled exhaust chest 36, thereby reducing the degree of exhaust therein somewhat and, since, as has been hereinbefore explained, reductions in controlled exhaust result in a reduction in regulated exhaust, regulated exhaust Will be somewhat reduced. The amount of the reduction may be determined by the size of the bleed opening 237, and the size of this bleed may be calculated to provide the desired reduction in regulated exhaust depending upon the Weight of the dampers and connected parts in any given instrument.

It will be observed, however, that if the diaphragm 4t2?) is in raised position closing and bleed 415, the chamber 238 the vent 40?) Will be maintained under exhaust from the controlled exhaust chest communicated through the duct 239. Under these condi'- tions, therefore, ifthe diaphragm 234 is i' lib to which the duct ofu .re

lowered by exhausting opening ot the 2 have no e'll'ect on controlled exhaust.

It may be noted, however, that the bleed 222) is connected is the largest oit the bleeds 41, la` and 117), so that at any time when the bleed 4:2?) is closed to the passage of air, reasonably high degrees exhaust are maintained in the controlled and regulated exhaust chests Under such concitions, therez ot less importance. to compensate ie weight ot the dampers when the xj-A :w \f.\'f "l l w 1x1/tl ln" penal .i operado, oecausU at ne ngaci mensiti the ratio ot the torce required to as the sott pedal mechanisms. In the ordinary grand piano action such as illustrated herein, sott pedal eltects are ordinarily obtained by lifting the hammers somewhat nearer to the strings in order that the blows transmitted thereby may be somewhat sottcned.

For this purpose., in the present embodiment automatic means have been provided, including a rail 2i() lying beneath the hammers which may be connected through the bell crank 2l1 and rod 2&2 to the movable lent et pneumatic 2&3. is will be apparent, it' the pneumatic 213 is collapsed the hammers 8 will be raised to a position somewhat closer to the springs. The pneumatic 2&3 is connected means of conduit 2111 to the valve cl amber 245 ot the valve unit 2&6, the exhaust chamber 247 ot said valve unit being connected through the conduit 24S te the source ot exhaust in a manner to he described more particularly hereinafter. The diaphragm chamber 249 olf the valve unit is connected through the duct 250 to the tracker vent 251.

lVhen the valve 252 of the valve unit 246 is in the position illustrated, pneumatic 213 is expanded under the influence ot spring 253 acting upon one arm ot' the bell crank lever 2431. It' a perforation in a note sheet crosses the tracker vent 251, however, valve is raised and pneumatic 2&3 is collapsed to raise the hammers S.

As previously described, the conduits 22. and 2-18 leading respectively to the exhaust chambers 22S and 247 `et the loud and so'lt pedal valve mechanismsI are connected to the main source ot exhaust. It has been desirable, however, in some instances to regu late the exhaust applied to the pedal valves and pneumatics in order that the action of the pedal mechanisms may be uniform at all times regardless ot changes wl ich may take place in high exhaust as created by the main source ot exhaust. For this reason conduits 22) and 24S are joined and are nccted through a conduit 25S to the lhamber 229 et the pedal pre `:ure regal-aim' 26". This regulator is also prov'ded with a` chamber 261 connected to the main source ot cxhaust through the conduit 262. Communication between the chambers 259 and 261 is had through a plurality of perforations 263 in the plate or screen 264, suoli communication being controlled by a flexible. curtain valve 265 connected to the end of the rofl 266. Also mounted on the rod 266 is the member 267 to which is connected the ilexihle sleeve 268. Communication between the chamber 259 and the chamber 269 behind the sleeve mechanism is maintained through the unrestricted passage 270. The end of the rod 266 is connected to a spring 271 which is also attached to the adjusting screw 272 carried by the bridge 273.

It the exhaust maintainedin chamber 259 tends to be reduced as by the influx of a large quantity ot' atn'lospheric air, the exhaust maintained in the chamber 269 acting on the sleeve mechanisms is thereby reduced and under the intluence ot the spring 271 valve 265 will uncove additional perforations 263 to p rmit additional air to bo *ithdrawn from the chaniber 259 thereby tending to increase the degree ot exhaust maintained therein. In a similar manner it the degree ot exhaust in the chamber 259 tends to increase above the desired amount, the sleeve mechanism and valve will be moved in a` direction to cover additional perforstions 263, thus reducing the amount of air withdrawn from the chamber 259 and reducing the exhaust therein.

Thus a suhstantiallv uniform degree of exhaust is maintained at all times as a supply tor operating the loud and sott pedal mechanisms and the crescendo mechanisms, regardless ot any variations which may occur in high exhaust produced by the pump. By varying the tension ot the spring 271, the exhaust supplied to these mechanisms may be adjusted to any suitable level as desired.

I claim as my invention:

1. In an automatic piano having the usual strings, in combination, hammer actions, and a plurality of striker pneumaties con nected thereto, a regulator for maintaining at said player pneumatics a substantially const-ant degree of' exhaust, a damper rail, means to lift said damper rail to permit free (fllvibration of the strings, and means to reduce the exhaust applied to said striker pneumatics when said damper rail is lifted.

2. In an automatic piano having the usual hammer actions, strings, dampers, striker pneumatics and action Wind chest, in combination, a damper pedal mechanism for lifting said dampers to permit free vibration of the strings, means to operate said mechanism automatically, and means to reduce exhaust in said action wind chest when said dampers are lifted.

3. In an automatic piano having the usual hammer actions, strings, dampers, striker pneumatics and action Wind chest, in combination, a damper pedal mechanism for lifting said dampers to permit free vibration of the strings, means to operate said mechanism automatically, means to maintain in said action Wind chest a plurality of different degrees of exhaust, and means to reduce exhaust in said action Wind chest when said dampers are lifted and when relatively low degrees of exhaust are maintained in said action Wind chest by said maintaining means.

4. In an automatic piano having the usual hammer actions, strings, dampers, striker pneumatics and action wind chest, in combination, means for lifting a plurality of said dampers simultaneously to permit free vibration of the strings, and means to reduce exhaust in said action wind chest when said dampers are lifted.

5. In an automatic pneumatic piano having the usual hammer actions, dampers, striker pneumatics and action wind chest, in combination, a damper rail, pneumatic means to lift said damper rail, means to maintain the exhaust for operating said pneumatic means at a substantially constant level, and means to reduce exhaust in said action Wind chest when said damper rail and dampers are lifted.

In testimony whereof, I have signed my name to this specification this 10th day of July, 1928.

CHARLES F. STODDARD. 

